{{Short description|Animal that feeds on carrion, dead plants, or refuse}} {{About||a person who scavenges|Waste picker|other uses}} [[File:Scavengers on the African Savannah.jpg|thumb|upright=1.2|White-backed vulture (''Gyps africanus''), lappet-faced vultures (''Torgos tracheliotos'') and marabou storks (''Leptoptilos crumenifer'') feeding on hyena carrion]] [[File: Crab-eating_Racoon_in_the_Trash.jpg|thumb|upright=1.2|A crab-eating raccoon (''Procyon cancrivorus'') scavenging in trash for food]]
'''Scavengers''' are animals that feed on dead and decaying organic matter.<ref name=":01">{{cite web|title=Scavenger (in Merriam-Webster Dictionary)|url= https://www.merriam-webster.com/dictionary/scavenger|publisher=Merriam-Webster|location=Springfield|access-date=August 18, 2025|date=2025}} See also: {{cite web|title=Scavenger (in Collins Dictionary)|url= https://www.collinsdictionary.com/dictionary/english/scavenger|publisher=HarperCollins|location=Glasgow|access-date=January 31, 2026|date=2026}}</ref><ref name=":02">{{cite web|title =Scavenger (in National Geographic)|url= https://education.nationalgeographic.org/resource/scavenger/|publisher=National Geographic Society|location=Washington DC|access-date=August 18, 2025|date=2025}}</ref> Often the term is used to describe the consumption of carrion, the bodies of animals that have died from causes other than predation or the bodies of animals that have been killed by other predators.<ref name=":03">{{cite journal |last1=Tan|first1=CKW|last2=Corlett|first2=RT |date=2011|title=Scavenging of dead invertebrates along an urbanisation gradient in Singapore |journal=Insect Conservation and Diversity |volume=5 |issue=2 |pages=138–145 |doi=10.1111/j.1752-4598.2011.00143.x |s2cid=86467187 |issn=1752-458X |url=http://scholarbank.nus.edu.sg/handle/10635/101631 }}</ref> However, the term is also used to describe animals that feed on rotting plant matter<ref name=":02"/><ref name=":04">{{cite journal |last1=Getz |first1=W |year=2011 |title=Biomass transformation webs provide a unified approach to consumer–resource modelling |journal=Ecology Letters |volume=14 |issue=2 |pages=113–124 |doi=10.1111/j.1461-0248.2010.01566.x |pmid=21199247 |pmc=3032891 |bibcode=2011EcolL..14..113G}}</ref> or refuse.<ref name=":01"/>
Vultures and burying beetles are examples of scavengers that feed on carrion,<ref name=":05">{{cite journal|last1=Cushnie|first1=TP|last2=Luang-In|first2=V|last3=Sexton |first3=DW|title=Necrophages and necrophiles: a review of their antibacterial defenses and biotechnological potential |journal=Critical Reviews in Biotechnology |date=2025 |volume=45 |issue=3 |pages=625–642|doi=10.1080/07388551.2024.2389175| pmid=39198023|url= https://hal.science/hal-04747748v1}}</ref> pink bud moth and stag beetle larvae are examples of scavengers that feed on rotting plant matter,<ref name=":13">{{cite journal|author=Areces-Berazain, F|title=''Pyroderces rileyi'' (pink scavenger caterpillar)|journal=CABI Compendium|date=2022|volume=|issue=|article-number=45989|doi= 10.1079/cabicompendium.45989|url= https://www.cabi.org/isc/datasheet/45989}}</ref><ref name=":07">{{cite journal|author=Songvorawit, N; Areekul Butcher, B; Chaisuekul, C|title= Decaying wood preference of stag beetles (Coleoptera: Lucanidae) in a tropical dry-evergreen forest |journal=Environmental Entomology|date=2017|volume=46|issue=6|pages=1322–1328|doi= 10.1093/ee/nvx143 |pmid= 29069306 }}</ref> and raccoons and squirrels are examples of scavengers that feed on refuse.<ref name=":06">{{cite web|author=Wu, KJ|title=Junk food is bad for you. Is it bad for raccoons?|url= https://www.theatlantic.com/science/archive/2023/02/wild-animals-eating-human-food-health-issues/673138/|publisher=The Atlantic|location=Washington, DC|access-date=August 18, 2025|date=2023}}</ref> Carrion-eating scavengers are called necrophages.<ref name=":14">{{cite book|last1 =Park|first1=C|last2=Allaby|first2=M|year =2017|title=Necrophage (in A Dictionary of Environment and Conservation)|page=288|edition=3rd|publisher=Oxford University Press|location=Oxford|isbn = 978-0-19-182632-0}} See also: {{cite web|title =Necrophage (in Oxford Reference)|url= https://www.oxfordreference.com/display/10.1093/oi/authority.20110803100226873|publisher=Oxford University Press|location=Oxford|access-date=August 26, 2025|date=2007}}</ref>
Scavengers play an important role in ecosystems by preventing the accumulation of decaying matter and helping to recycle nutrients.<ref name=":02"/><ref name=":19">{{cite journal |author=Walker, JR; Evans, KL; Jeffreys, RM; Pahlevani, M; Parr, CL|year=2024 |title=Urban scavenging: vertebrates display greater sensitivity to land-cover and garden vegetation cover than invertebrates|journal=Urban Ecosystems|volume=27 |issue=6|pages=2557–2567|doi=10.1007/s11252-024-01604-3|bibcode=2024UrbEc..27.2557W |doi-access=free}}</ref> The process and rate at which dead plant and animal material is scavenged is affected by both biotic and abiotic factors, such as plant species, carcass size, habitat, temperature, moisture levels, and seasons.<ref name="Ecology2017">{{cite journal |last1=Turner|first1=KL|last2=Abernethy|first2=EF|last3=Conner|first3=LM|last4=Rhodes|first4=OE|last5=Beasley |first5=JC|date=2017 |title=Abiotic and biotic factors modulate carrion fate and vertebrate scavenging communities |journal=Ecology|volume=98|issue=9|pages=2413–2424|doi=10.1002/ecy.1930|pmid=28628191|issn=0012-9658|doi-access=free |bibcode=2017Ecol...98.2413T}}</ref><ref name=":09">{{cite journal|author=Leung, TKC; Bonebrake, TC|title= Abundance, distribution and substrate association of Hong Kong stag beetles (Coleoptera: Lucanidae) in secondary forests|journal=Insect Conservation and Diversity|date=2021|volume=14 |issue=5|pages=609–619|doi=10.1111/icad.12492}}</ref><ref name=":10">{{cite journal|author=Thomaes, A; Christiaens, B; Goessens, S; Tagliani, A|title=Evaluating log piles as stag beetle conservation measure|journal=Journal of Insect Conservation|date=2024|volume=28 |issue=4|pages=811–819|doi=10.1007/s10841-024-00603-1 |bibcode=2024JICon..28..811T }}</ref> Detritivores and decomposers complete this process by consuming the remains left by scavengers.<ref name=":15"/><ref name=":08">{{cite journal|author=DeBruyn, JM; Keenan, SW; Taylor, LS|title=From carrion to soil: microbial recycling of animal carcasses|journal=Trends in Microbiology|date=2025|volume=33 |issue=2|pages=194–207|doi=10.1016/j.tim.2024.09.003| pmid=39358066}}</ref>
== Etymology == Scavenger is an alteration of ''scavager,'' from Middle English ''skawager'' meaning "customs collector", from ''skawage'' meaning "customs", from Old North French ''escauwage'' meaning "inspection", from ''schauwer'' meaning "to inspect", of Germanic origin; akin to Old English ''scēawian'' and German ''schauen'' meaning "to look at", and modern English "show" (with semantic drift).<ref name=":27">{{cite book|last1=Campbell |first1=MON|title=Vultures: Their Evolution, Ecology and Conservation|date=2015|publisher=CRC Press|location=Boca Raton|isbn=978-1-4822-2362-0|pages=1–6 |chapter=Vulture classification, genetics and ecology}}</ref>
== Related terminology == Animals that subsist entirely or mainly on decaying biomass (e.g. dead animals, dead plants) are called obligate scavengers, while those capable of obtaining food via other methods are termed facultative scavengers.<ref name=":24">{{cite web|author=Graham, D|title=Scavengers: What are they, why are they important and just how do scavengers find their food? All your questions answered|url= https://www.discoverwildlife.com/animal-facts/what-are-scavengers|publisher=BBC Wildlife|location=Bristol|access-date=September 6, 2025|date=2024}}</ref> Animals that rely specifically on carrion as a food source are called obligate necrophages.<ref name=":05"/><ref name=":25">{{cite journal|author=Maccaro, JJ; Figueroa, LL; McFrederick, QS|title= From pollen to putrid: comparative metagenomics reveals how microbiomes support dietary specialization in vulture bees|journal=Molecular Ecology|date=2024|volume=33|issue=3|article-number= e17421|doi=10.1111/mec.17421|pmid=38828760|bibcode= 2024MolEc..33E7421M|doi-access=free}}</ref> Animals that feed on particulate plant or animal matter (e.g. humus, marine snow) are typically categorized as detritivores rather than scavengers.<ref name=":15">{{cite web|title=Detritivore (in Biology Dictionary)|website= Biology Dictionary| date=2019|url= https://biologydictionary.net/detritivore/|access-date=August 26, 2025|archive-url=https://web.archive.org/web/20250713011225/https://biologydictionary.net/detritivore/|archive-date=July 13, 2025}}</ref> The midge fly ''Propsilocerus akamusi'', which feeds on detritus in the sediment of freshwater lakes, is an example of a detritivore.<ref name=":26">{{cite journal|author=Zou, W; Cai, Y; Tolonen, KT; Zhu, G; Qin, B; Peng, K; Gong, Z |title=The adaptations to tube-dwelling life of ''Propsilocerus akamusi'' (Diptera: Chironomidae) larvae and its eutrophication-tolerant mechanisms|journal=Limnologica|date=2019|volume=77|issue= |article-number=125684|doi=10.1016/j.limno.2019.125684 |bibcode=2019Limng..7725684Z }}</ref>
== Types of scavengers == ===Scavengers that feed on carrion=== {{Main|Necrophage}} [[File:Buitres leonados (Gyps fulvus) 0.jpg|thumb|right|upright=1.1|Griffon vultures (''Gyps fulvus'') eating the carcass of a red deer in Spain]] Obligate scavenging of carrion (obligate necrophagy) is rare among vertebrates, due to the difficulty of finding enough carrion without expending too much energy.<ref name=":12">{{cite journal |last1=DeVault |first1=TL |last2= Rhodes |first2=OE |last3= Shivik |first3=JA|title= Scavenging by vertebrates: behavioral, ecological, and evolutionary perspectives on an important energy transfer pathway in terrestrial ecosystems |journal= Oikos|date=2003 |volume=102 |issue= 2|pages=225–234 |doi= 10.1034/j.1600-0706.2003.12378.x|bibcode=2003Oikos.102..225D }}</ref> New World vultures such as the black vulture, and Old World vultures such as the griffon vulture, white-backed vulture and lappet-faced vulture, are examples of obligate carrion scavengers.<ref name=":05"/>
Most of the vertebrates that eat carrion are facultative scavengers, capable of obtaining food via predation or other methods, and eating carrion opportunistically.<ref name=":05"/> Many large carnivores that hunt regularly, such as hyenas and jackals, but also animals rarely thought of as scavengers, such as African lions, leopards, and wolves will scavenge if given the chance.<ref name=":02"/> They may also use their size and ferocity to intimidate the original hunters into abandoning their kills (the cheetah is a notable victim, rather than a perpetrator).<ref name=":22">{{cite book |last1=Sunquist |first1=F. |last2=Sunquist |first2=M. |name-list-style=amp |title=Wild Cats of the World |date=2002 |publisher=The University of Chicago Press |location=Chicago |isbn=978-0-226-77999-7 |pages=19–36 |chapter=Cheetah ''Acinonyx jubatus'' (Schreber, 1776) |chapter-url={{Google Books |plainurl=yes |id=hFbJWMh9-OAC |page=19}} }}</ref> Gulls, crows and magpies frequently scavenge roadkill.<ref name=":23">{{cite journal|author=Schwartz, ALW; Williams, HF; Chadwick, E; Thomas, RJ; Perkins, SE|title=Roadkill scavenging behaviour in an urban environment|journal=Journal of Urban Ecology|date=2018|volume=4|issue=1 |pages=1–7 |doi=10.1093/jue/juy006}}</ref> Other vertebrates, for example Egyptian mastigures, scavenge to survive during times of food scarcity.<ref>{{cite journal |last1=Castilla |first1=AM|last2=Richer|first2=R|last3=Herrel|first3=A|last4=Conkey|first4=AAT|last5=Tribuna |first5=J|last6=Al-Thani |first6=M|date=2011 |title=First evidence of scavenging behaviour in the herbivorous lizard ''Uromastyx aegyptia microlepis''|journal=Journal of Arid Environments|volume=75 |issue=7 |pages=671–673 |doi=10.1016/j.jaridenv.2011.02.005 |issn=0140-1963 |bibcode=2011JArEn..75..671C}}</ref>
Aquatic and semi-aquatic vertebrates feed on carrion too. Carrion-eating scavengers found in marine settings include hagfish, great white sharks, northern wolffish and abyssal grenadiers, and carrion-eating scavengers found in freshwater settings include American alligators, Eurasian otters and common midwife toads.<ref name=":05"/>
[[File:Sarcophaga nodosa.jpg|thumb|upright=1.1|''Sarcophaga nodosa'', a species of flesh fly, feeding on decaying meat]] Burying beetles, vulture bees and bone skipper flies are examples of obligately necrophagous invertebrates. They are all dependent on carrion during the larval stages of their life cycles. Adult burying beetles and vulture bees feed on carrion too.<ref name=":05"/><ref name=":11">{{cite journal |last1=Gilliam |first1=M |last2=Buchmann |first2=SL |last3=Lorenz |first3=BJ |last4=Roubik |first4=DW |title=Microbiology of the larval provisions of the stingless bee, ''Trigona hypogea'', an obligate necrophage |journal=Biotropica |date=1985 |volume=17 |issue=1 |page=28 |doi=10.2307/2388374 |jstor=2388374 |bibcode=1985Biotr..17...28G }}</ref> Other invertebrates, such as blow flies, flesh flies and yellowjackets, also feed on carrion but are not reliant on it for survival.<ref name=":05"/> Blow fly and flesh fly larvae can feed on excrement, and some species, for example, ''Chrysomya putoria'' and ''Sarcophaga crassipalpis'', can feed on living tissue.<ref name=":05"/><ref name=":16">{{Cite book| vauthors = Allen JC, Anderson GS, Benecke M et al |title= Forensic Entomology: The Utility of Arthropods in Legal Investigations |date=2001|publisher= CRC Press| veditors = Byrd JH, Castner JL |isbn=978-0-8493-8120-1| pages=43-80, 143-176, 177-222, 263-286, 331-340 |location=London}}</ref> Also, yellowjackets can hunt caterpillars and other insects and feed on nectar, sap and fruit.<ref name=":17">{{cite journal |last1=Richter|first1=MR|title= Social wasp (Hymenoptera: Vespidae) foraging behavior|journal=Annual Review of Entomology|date=2000|volume=45|issue=|pages=121–150|doi=10.1146/annurev.ento.45.1.121|pmid=10761573}}</ref><ref name=":18">{{cite journal|author= Brock, RE; Cini, A; Sumner, S|title=Ecosystem services provided by aculeate wasps|journal=Biological Reviews of the Cambridge Philosophical Society|date=2021|volume=96|issue=4|pages=1645–1675|doi=10.1111/brv.12719|pmid=33913243 |bibcode=2021BioRv..96.1645B }}</ref>
In addition to the terrestrial examples above, many aquatic invertebrates consume carrion. The common octopus, European green crab and seven-armed starfish are all marine invertebrates that feed on carrion, and the ribbon leech ''Erpobdella obscura'' and red swamp crayfish are freshwater invertebrates that feed on carrion.<ref name=":05"/>
Carrion-eating scavengers have numerous adaptations to help them find food (e.g. excellent eyesight and hearing, strong sense of smell),<ref name=":12"/><ref name=":34">{{cite journal |author=Jackson, CR; Maddox T; Mbise, FP; Stokke, BG; Belant, JL; Bevanger, K; Durant, SM; Fyumagwa, R; Ranke, PS; Røskaft, E; May, R; Fossøy F|title=A dead giveaway: foraging vultures and other avian scavengers respond to auditory cues| journal=Ecology and Evolution|date=2020|volume=10|issue=13 |pages=6769–6774 |doi=10.1002/ece3.6366|pmid=32724549|pmc=7381568 |bibcode=2020EcoEv..10.6769J }}</ref><ref name=":35">{{cite journal |last1= Kalinová |first1=B|last2=Podskalská |first2=H|last3=Růzicka |first3=J|last4=Hoskovec|first4=M|title= Irresistible bouquet of death-how are burying beetles (Coleoptera: Silphidae: ''Nicrophorus'') attracted by carcasses |journal=Naturwissenschaften|date=2009 |volume=96 |issue=8|pages=889–99|doi= 10.1007/s00114-009-0545-6|pmid=19404598|bibcode=2009NW.....96..889K}}</ref> protect themselves from infection and intoxication (e.g. strong immune systems, toxin-resistant physiologies),<ref name=":05"/><ref name=":36">{{cite web|vauthors = Cushnie T, Sexton D, Luang-In V |title = Antibacterial discovery: how scavengers avoid infection and what we can learn from them|url= https://theconversation.com/antibacterial-discovery-how-scavengers-avoid-infection-and-what-we-can-learn-from-them-229828|publisher=The Conversation|access-date=December 1, 2025|date=September 2024}}</ref> gorge themselves when food is available (e.g. expandable intestines),<ref name=":37">{{cite journal |last1=Duffy |first1=GA|last2=Gutteridge|first2=ZR |last3=Thurston |first3=MH |last4=Horton|first4=T|title=A comparative analysis of canyon and non-canyon populations of the deep-sea scavenging amphipod ''Paralicella caperesca''|journal= Journal of the Marine Biological Association of the United Kingdom |date=2016|volume=96 |issue= 8|pages=1687–1699|doi=10.1017/S0025315415002064 |bibcode=2016JMBUK..96.1687D }}</ref> and conserve energy between meals (e.g. gliding flight).<ref name=":12"/>
===Scavengers that feed on dead plants=== [[File: Lucanus cervus larva inside a log.jpg|thumb|upright=1.1|The stag beetle, ''Lucanus cervus'', feeding on dead wood during the larval stage of its life cycle]] Animals that feed on dead plant material are called herbivorous scavengers.<ref name=":38">{{cite journal |last1=Moore|first1=JW|title=Importance of algae in the diet of subarctic populations of ''Gammarus lacustris'' and ''Pontoporeia affinis''|journal=Canadian Journal of Zoology|date=1977|volume=55|issue=3|pages=637–641|doi=10.1139/z77-083 |bibcode=1977CaJZ...55..637M }}</ref><ref name=":39">{{cite journal |last1=Kostanjsek|first1=R|last2=Strus|first2=J|last3=Avgustin |first3=G|title="''Candidatus'' Bacilloplasma," a novel lineage of ''Mollicutes'' associated with the hindgut wall of the terrestrial isopod ''Porcellio scaber'' (Crustacea: Isopoda)|journal= Applied and Environmental Microbiology|date=2007|volume=73|issue=17|pages=5566–5573|doi= 10.1128/AEM.02468-06|pmid= 17630315|pmc=2042062|bibcode=2007ApEnM..73.5566K}}</ref>
Some stag beetles are obligate scavengers of dead plant material. For example, ''Lucanus cervus'' is dependent on dead wood during the larval stages of its life cycle.<ref name=":21">{{cite web|title =Stag beetle: how to help its conservation in London|url= https://www.wildlondon.org.uk/sites/default/files/2019-06/stag-beetle-london-wildlife-trust-advice-note-2016.pdf|publisher=London Wildlife Trust|location=London|access-date=September 1, 2025|date=2016}}</ref> Adult ''Lucanus cervus'' beetles lay their eggs near the stumps of dead trees, and the larvae then spend the next 4 to 7 years feeding and growing in size. Types of wood eaten include oak, ash, elm, sycamore, lime and hornbeam.<ref name=":21"/>
Pink bud moth larvae (also known as pink scavenger caterpillars) are facultative scavengers of dead plant material, feeding on rotting fruits, decaying flowers and leaves, but also the fruits and grains of live plants.<ref name=":13"/> Termites are facultative scavengers too. Termites feed on dead trees and wood, but also live plants and detritus such as humus and excrement.<ref name=":29">{{cite web|author=Ondrizek, M|title=Study: termites may have a larger role in future ecosystems|url= https://news.umich.edu/study-termites-may-have-a-larger-role-in-future-ecosystems/|publisher=University of Michigan|location=Ann Arbor|access-date=September 9, 2025|date=2022}}</ref><ref name=":30">{{cite journal |last1=Freymann |first1=BP|last2=Buitenwerf |first2=R|last3=Desouza |first3=O|last4=Olff|first4=H|title=The importance of termites (Isoptera) for the recycling of herbivore dung in tropical ecosystems: a review |journal=European Journal of Entomology |date=2008 |volume=105 |issue=2 |pages=165–173 |doi=10.14411/eje.2008.025 |doi-access=free}}</ref> Darkling beetles (tenebrionids),<ref name=":31">{{cite journal|author=Driscoll, DA; Smith, AL; Blight, S; Sellar, I|title=Interactions among body size, trophic level, and dispersal traits predict beetle detectability and occurrence responses to fire|journal=Ecological Entomology |date=2020|volume=45 |issue=2|pages=300–310 |doi=10.1111/een.12798 |bibcode=2020EcoEn..45..300D |url=https://figshare.com/articles/journal_contribution/20740066 }}</ref> woodlice,<ref name=":39"/> and banana moth larvae<ref name=":32">{{cite journal|author=Nelson, S; Wright, M|title=Banana moth—a potentially fatal pest of ''Pritchardia'' and other palms |journal=Insect Pests|date=2005|volume=|issue=|pages=1–4 |url=https://www.ctahr.hawaii.edu/oc/freepubs/pdf/ip-24.pdf}}</ref> are also facultative scavengers of dead plant material.
===Scavengers that feed on discarded food=== [[File: Seagull scavenge trash bin 2.jpg|thumb|upright=1.1|An urban gull scavenging in a garbage can for food]] In urban settings, some animals regularly explore public parks and garbage cans for discarded food items that they can eat.<ref name=":19"/><ref name=":41"/> This type of scavenger is sometimes called a refuse eater.<ref name=":43">{{cite journal|author=Oliver, WT|title=Poisons and Poisoning|journal=Canadian Journal of Comparative Medicine and Veterinary Science|date=1956|volume=20|issue=10|pages=382–7|pmid=17648918|pmc=1614332}}</ref><ref name=":44">{{cite journal|author= Sapolsky, RM; Share, LJ |title= A pacific culture among wild baboons: its emergence and transmission|journal=PLOS Biology |date=2004|volume=2|issue=4|pages=E106|pmid=15094808|doi=10.1371/journal.pbio.0020106|doi-access= free|pmc= 387274}}</ref> Vertebrate examples include gulls,<ref name=":02"/> crows,<ref name=":06"/><ref name=":41">{{cite journal |vauthors = Biswas S, Bhowmik T, Ghosh K, Roy A, Lahiri A, Sarkar S, Bhadra A|title=Scavengers in the human-dominated landscape: an experimental study|journal=Philosophical Transactions of the Royal Society B|date=2024|volume=379|issue=1909|article-number=20230179| doi=10.1098/rstb.2023.0179}}</ref> feral pigeons,<ref name=":19"/> raccoons,<ref name=":06"/> baboons,<ref name=":40"/> opossums,<ref name=":02"/> brown rats,<ref name=":19"/> and squirrels.<ref name=":06"/><ref name=":41"/> Invertebrate examples include ants and blow flies.<ref name=":02"/><ref name=":19"/> In areas where there are municipal dumps, polar bears,<ref name=":02"/> elephants,<ref name=":40">{{cite web|author=Gorvett, Z; Gerretsen, I; Gray, R; Sherriff, L; Dowling, S; Bourke, I; Henriques, M|title =The scavengers stalking the world's cities|url= https://www.bbc.com/future/article/20240423-the-scavengers-stalking-the-worlds-cities/|publisher=BBC|location=London|access-date=February 3, 2026|date=2024}}</ref><ref name=":42">{{cite journal |vauthors =Liyanage DJ, Fernando P, Nihal Dayawansa P, Janaka HK, Pastorini J|title=The elephant at the dump: how does garbage consumption impact Asian elephants?|journal=Mammalian Biology|date=2021|volume=101|issue=6|pages=1089–1097| doi=10.1007/s42991-021-00114-5}}</ref> raccoon dogs, red foxes, martens and polecats sometimes scavenge for food.<ref name=":20">{{cite journal |author=Jankowiak, Ł; Malecha, AW; Krawczyk, AJ|title=Garbage in the diet of carnivores in an agricultural area|journal=European Journal of Ecology|date=2016|volume=2|issue=1|pages=81–86|doi=10.1515/eje-2016-0009}}</ref> Hyenas also scavenge from municipal dumps in some prey-depleted districts of East Africa.<ref name=":28">{{Cite journal |last1=Yirga |first1=G|last2=Leirs|first2=H|last3=De Longh|first3=HH|last4=Asmelash |first4=T|last5=Gebrehiwot |first5=K|last6=Deckers |first6=J |last7=Bauer|first7=H|date=2015|title=Spotted hyena (''Crocuta crocuta'') concentrate around urban waste dumps across Tigray, northern Ethiopia|journal=Wildlife Research|language=en |volume=42|issue=7|pages=563–569|doi=10.1071/WR14228 |bibcode=2015WildR..42..563Y|s2cid=86458636|issn=1448-5494}}</ref>
The type of refuse eaten may be of plant origin (e.g. fruits, vegetables, leaves),<ref name=":42"/> animal origin (e.g. slaughterhouse discards),<ref name=":28"/> or it may be prepared food (e.g. cooked rice, bakery items).<ref name=":42"/>
== Prehistoric scavengers == In the prehistoric eras, the species ''Tyrannosaurus rex'' may have been an apex predator, preying upon hadrosaurs, ceratopsians, and possibly juvenile sauropods,<ref>{{cite journal |url=http://blogs.smithsonianmag.com/dinosaur/2012/04/when-tyrannosaurus-chomped-sauropods/ |title=When Tyrannosaurus Chomped Sauropods |journal=Journal of Vertebrate Paleontology |volume=25 |issue=2 |pages=469–472 |last=Switeck |first=Brian |date=April 13, 2012 |access-date=August 24, 2013 |doi=10.1671/0272-4634(2005)025[0469:TRFTUC]2.0.CO;2 |s2cid=131583311|url-access=subscription }}</ref> although some experts have suggested the dinosaur was primarily a scavenger. The debate about whether ''Tyrannosaurus'' was an apex predator or scavenger was among the longest ongoing feuds in paleontology; however, most scientists now agree that ''Tyrannosaurus'' was an opportunistic carnivore, acting mostly as a predator but also scavenging when it could sense it.<ref>{{cite web |url=http://whatsinjohnsfreezer.com/2013/07/15/trex_scavenger_stfu/ |title=Tyrannosaurus rex: predator or media hype? |last=Hutchinson |first=John |publisher=What's in John's Freezer? |date=July 15, 2013 |access-date=August 26, 2013}}</ref> Recent research also shows that while an adult ''T. rex'' would energetically gain little through scavenging, smaller theropods of approximately {{cvt|500|kg|lb}} might have gained levels similar to those of hyenas, though not enough for them to rely on scavenging.<ref>{{cite journal |url=https://healyke.github.io/Latexcv/Dino_proof.pdf |title=Body Size as a Driver of Scavenging in Theropod Dinosaurs |last=Kane |display-authors=etal |journal=The American Naturalist |date=2016 |volume=187 |issue=6 |pages=706–16 |doi=10.1086/686094 |pmid=27172591 |bibcode=2016ANat..187..706K |hdl=10023/10617 |s2cid=3840870 |hdl-access=free}}</ref>
Other research suggests that carcasses of giant sauropods may have made scavenging much more profitable to carnivores than it is now. For example, a single 40 tonne ''Apatosaurus'' carcass would have been worth roughly 6 years of calories for an average allosaur. As a result of this resource oversupply, it is possible that some theropods evolved to get most of their calories by scavenging giant sauropod carcasses, and may not have needed to consistently hunt in order to survive.<ref>{{cite journal |url=https://www.sciencedirect.com/science/article/pii/S0304380021002611 |title=Carnosaurs as Apex Scavengers: Agent-based simulations reveal possible vulture analogues in late Jurassic Dinosaurs |last=Pahl and Ruedas |journal=Ecological Modelling |date=2021 |volume=458 |article-number=109706 |doi=10.1016/j.ecolmodel.2021.109706 |bibcode=2021EcMod.45809706P|url-access=subscription }}</ref><ref>{{Cite journal |last1=Pahl |first1=Cameron C. |last2=Ruedas |first2=Luis A. |date=2023-11-01 |title=Big boned: How fat storage and other adaptations influenced large theropod foraging ecology |journal=PLOS ONE |language=en |volume=18 |issue=11 |article-number=e0290459 |doi=10.1371/journal.pone.0290459 |issn=1932-6203 |pmc=10619836 |pmid=37910492 |doi-access=free |bibcode=2023PLoSO..1890459P}}</ref> The same study suggested that theropods in relatively sauropod-free environments, such as tyrannosaurs, were not exposed to the same type of carrion oversupply, and were therefore forced to hunt in order to survive.
== Ecological function == Scavengers play a fundamental role in the environment through the removal of decaying organisms, serving as a natural sanitation service.<ref name="DroppingDead2011">{{cite journal |last1=Ogada |first1=Darcy L. |last2=Keesing |first2=Felicia |last3=Virani |first3=Munir Z. |date=16 December 2011 |title=Dropping dead: causes and consequences of vulture population declines worldwide |journal=Annals of the New York Academy of Sciences |volume=1249 |issue=1 |pages=57–71 |doi=10.1111/j.1749-6632.2011.06293.x |pmid=22175274 |issn=0077-8923 |bibcode=2012NYASA1249...57O |s2cid=23734331}}</ref> While microscopic and invertebrate decomposers break down dead organisms into simple organic matter which are used by nearby autotrophs, scavengers help conserve energy and nutrients obtained from carrion within the upper trophic levels, and are able to disperse the energy and nutrients farther away from the site of the carrion than decomposers.<ref>{{cite journal |last1=Olson |first1=Zachary H. |last2=Beasley |first2=James C. |last3=Rhodes |first3=Olin E. |date=2016-02-17 |title=Carcass Type Affects Local Scavenger Guilds More than Habitat Connectivity |journal=PLOS ONE |volume=11 |issue=2 |article-number=e0147798 |doi=10.1371/journal.pone.0147798 |pmid=26886299 |pmc=4757541 |issn=1932-6203 |bibcode=2016PLoSO..1147798O |doi-access=free}}</ref>
Scavenging unites animals which normally would not come into contact,<ref>{{cite journal |last1=Dunlop |first1=Kathy M. |last2=Jones |first2=Daniel O. B. |last3=Sweetman |first3=Andrew K. |date=December 2017 |title=Direct evidence of an efficient energy transfer pathway from jellyfish carcasses to a commercially important deep-water species |journal=Scientific Reports |volume=7 |issue=1 |page=17455 |doi=10.1038/s41598-017-17557-x |pmid=29234052 |pmc=5727084 |issn=2045-2322 |bibcode=2017NatSR...717455D}}</ref> and results in the formation of highly structured and complex communities which engage in nonrandom interactions.<ref name="Oikos2011">{{cite journal |last1=Olson |first1=Z. H. |last2=Beasley |first2=J. C. |last3=DeVault |first3=T. L. |last4=Rhodes |first4=O. E. |date=31 May 2011 |title=Scavenger community response to the removal of a dominant scavenger |journal=Oikos |volume=121 |issue=1 |pages=77–84 |doi=10.1111/j.1600-0706.2011.19771.x |issn=0030-1299 |url=https://digitalcommons.unl.edu/icwdm_usdanwrc/1085|url-access=subscription }}</ref> Scavenging communities function in the redistribution of energy obtained from carcasses and reducing diseases associated with decomposition. Oftentimes, scavenger communities differ in consistency due to carcass size and carcass types, as well as by seasonal effects as consequence of differing invertebrate and microbial activity.<ref name="Ecology2017" />
Competition for carrion results in the inclusion or exclusion of certain scavengers from access to carrion, shaping the scavenger community. When carrion decomposes at a slower rate during cooler seasons, competitions between scavengers decrease, while the number of scavenger species present increases.<ref name="Ecology2017" />
Alterations in scavenging communities may result in drastic changes to the scavenging community in general, reduce ecosystem services and have detrimental effects on animal and humans.<ref name="Oikos2011" /> The reintroduction of gray wolves (''Canis lupus'') into Yellowstone National Park in the United States caused drastic changes to the prevalent scavenging community, resulting in the provision of carrion to many mammalian and avian species.<ref name="Ecology2017" /> Likewise, the reduction of vulture species in India lead to the increase of opportunistic species such as feral dogs and rats. The presence of both species at carcasses resulted in the increase of diseases such as rabies and bubonic plague in wildlife and livestock, as feral dogs and rats are transmitters of such diseases. Furthermore, the decline of vulture populations in India has been linked to the increased rates of anthrax in humans due to the handling and ingestion of infected livestock carcasses. An increase of disease transmission has been observed in mammalian scavengers in Kenya due to the decrease in vulture populations in the area, as the decrease in vulture populations resulted in an increase of the number of mammalian scavengers at a given carcass along with the time spent at a carcass.<ref name="DroppingDead2011" />
=== Disease transmission === Scavenging may provide a direct and indirect method for transmitting disease between animals.<ref name="Sci. Rep.">{{cite journal |last1=Maák |first1=István |last2=Tóth |first2=Eszter |last3=Lőrinczi |first3=Gábor |last4=Kiss |first4=Annett |last5=Juhász |first5=Orsolya |last6=Czechowski |first6=Wojciech |last7=Torma |first7=Attila |last8=Lenda |first8=Madalena |date=October 2020 |title=Behaviours indicating cannibalistic necrophagy in ants are modulated by the perception of pathogen infection level |journal=Scientific Reports |publisher=Nature Research |volume=10 |issue=17906 |page=17906 |doi=10.1038/s41598-020-74870-8 |doi-access=free |pmc=7578781 |pmid=33087857 |bibcode=2020NatSR..1017906M |s2cid=224819566}}</ref> Scavengers of infected carcasses may become hosts for certain pathogens and consequently vectors of disease themselves.<ref name="Sci. Rep."/> An example of this phenomenon is the increased transmission of tuberculosis observed when scavengers engage in eating infected carcasses.<ref>{{cite journal |last1=Carrasco-Garcia |first1=Ricardo |last2=Barroso |first2=Patricia |last3=Perez-Olivares |first3=Javier |last4=Montoro |first4=Vidal |last5=Vicente |first5=Joaquín |date=2 March 2018 |title=Consumption of Big Game Remains by Scavengers: A Potential Risk as Regards Disease Transmission in Central Spain |journal=Frontiers in Veterinary Science |volume=5 |article-number=4 |doi=10.3389/fvets.2018.00004 |pmid=29552564 |pmc=5840163 |issn=2297-1769 |doi-access=free}}</ref> Likewise, the ingestion of bat carcasses infected with rabies by striped skunks (''Mephitis mephitis'') resulted in increased infection of these organisms with the virus.
A major vector of transmission of diseases are various bird species, with outbreak being influenced by such carrier birds and their environment. An avian cholera outbreak from 2006 to 2007 off the coast Newfoundland, Canada resulted in the mortality of many marine bird species. The transmission, perpetuation and spread of the outbreak was mainly restricted to gull species who scavenge for food in the area.<ref>{{cite journal |last1=Wille |first1=Michelle |last2=McBurney |first2=Scott |last3=Robertson |first3=Gregory J. |last4=Wilhelm |first4=Sabina I. |last5=Blehert |first5=David S. |last6=Soos |first6=Catherine |last7=Dunphy |first7=Ron |last8=Whitney |first8=Hugh |title=A Pelagic Outbreak of Avian Cholera in North American Gulls: Scavenging as a Primary Mechanism for Transmission? |date=October 2016 |journal=Journal of Wildlife Diseases |volume=52 |issue=4 |pages=793–802 |doi=10.7589/2015-12-342 |pmid=27455197 |bibcode=2016JWDis..52..793W |issn=0090-3558 |doi-access=free}}</ref> Similarly, an increase of transmission of avian influenza virus to chickens by domestic ducks from Indonesian farms permitted to scavenge surrounding areas was observed in 2007. The scavenging of ducks in rice paddy fields in particular resulted in increased contact with other bird species feeding on leftover rice, which may have contributed to increased infection and transmission of the avian influenza virus. The domestic ducks may not have demonstrated symptoms of infection themselves, though were observed to excrete high concentrations of the avian influenza virus.<ref>{{cite journal |last1=Henning |first1=Joerg |last2=Wibawa |first2=Hendra |last3=Morton |first3=John |last4=Usman |first4=Tri Bhakti |last5=Junaidi |first5=Akhmad |last6=Meers |first6=Joanne |date=August 2010 |title=Scavenging Ducks and Transmission of Highly Pathogenic Avian Influenza, Java, Indonesia |journal=Emerging Infectious Diseases |volume=16 |issue=8 |pages=1244–1250 |doi=10.3201/eid1608.091540 |pmid=20678318 |pmc=3298304 |issn=1080-6040}}</ref>
== Threats == {{Off topic|date=November 2018|Vulture}}
Many species that scavenge face persecution globally.{{citation needed|date=December 2018}} Vultures, in particular, have faced incredible persecution and threats by humans. Before its ban by regional governments in 2006, the veterinary drug Diclofenac has resulted in at least a 95% decline of ''Gyps'' vultures in Asia. Habitat loss and food shortage have contributed to the decline of vulture species in West Africa due to the growing human population and over-hunting of vulture food sources, as well as changes in livestock husbandry. Poisoning certain predators to increase the number of game animals is still a common hunting practice in Europe and contributes to the poisoning of vultures when they consume the carcasses of poisoned predators.<ref name="DroppingDead2011" />
== Benefits to humans == {{further|Necrophage#Current roles and uses|Necrophage#Other possible uses}} Highly efficient scavengers, also known as dominant or apex-scavengers, can have benefits to humans. Increases in dominant scavenger populations, such as vultures, can reduce populations of smaller opportunistic scavengers, such as rats.<ref>{{Cite journal |last1=O'Bryan |first1=Christopher J. |last2=Holden |first2=Matthew H. |last3=Watson |first3=James E. M. |title=The mesoscavenger release hypothesis and implications for ecosystem and human well-being |journal=Ecology Letters |language=en |doi=10.1111/ele.13288 |issn=1461-0248 |year=2019 |volume=22 |issue=9 |pages=1340–1348 |pmid=31131976 |bibcode=2019EcolL..22.1340O |s2cid=167209009}}</ref> These smaller scavengers are often pests and disease vectors.
==In humans== {{See also|Human cannibalism|Roadkill cuisine}} [[File:Bundesarchiv Bild 183-R77871, Berlin, Einwohner zerlegen ein Pferd.jpg|thumb|upright=1.25|Men scavenging a dead horse during World War II (at the end of the Battle of Berlin), on Manfred-von-Richthofen-Straße in Tempelhof borough, 1945]]
In the 1980s, Lewis Binford suggested that early humans primarily obtained meat via scavenging, not through hunting.<ref>{{cite journal |last=Binford |first=Lewis R. |author-link=Lewis Binford |date=December 1985 |title=Human Ancestors: Changing Views of Their Behavior |journal=Journal of Anthropological Archaeology |publisher=Elsevier |volume=4 |issue=4 |doi=10.1016/0278-4165(85)90009-1 |pages=292–327 |issn=0278-4165 |lccn=82644021 |oclc=637806874 |s2cid=144619876}}</ref> In 2010, Dennis Bramble and Daniel Lieberman proposed that early carnivorous human ancestors subsequently developed long-distance running behaviors which improved the ability to scavenge and hunt: they could reach scavenging sites more quickly and also pursue a single animal until it could be safely killed at close range due to exhaustion and hyperthermia.<ref>{{cite conference |url=http://nrs.harvard.edu/urn-3:HUL.InstRepos:3716644 |title=The Evolution of Marathon Running: Capabilities in Humans |last1=Lieberman |first1=Daniel |last2=Bramble |first2=Dennis |year=2007 |publisher=Adis Data Information BV |doi=10.2165/00007256-200737040-00004 |page=288 |access-date=2017-03-15 |quote=Human endurance running performance capabilities compare favourably with those of other mammals and probably emerged sometime around 2 million years ago in order to help meat-eating hominids compete with other carnivores. [...] [S]mall teeth, larger bodies and archaeological remains suggest that hominids started to incorporate meat and other animal tissues in the diet at least 2.5Ma, probably by hunting as well as scavenging. [...] [Endurance running] might have enabled hominids to scavenge carcasses from lions after they were abandoned but before hyenas arrived, as modern hunter-gatherers still do in East Africa.|url-access=subscription }}</ref>
In Tibetan Buddhism, the practice of excarnation—that is, the exposure of dead human bodies to carrion birds and/or other scavenging animals—is the distinctive characteristic of sky burial, which involves the dismemberment of human cadavers of whom the remains are fed to vultures, and traditionally the main funerary rite (alongside cremation) used to dispose of the human body.<ref>{{cite book |last=Kapstein |first=Matthew T. |author-link=Matthew Kapstein |year=2014 |chapter=Funeral customs |chapter-url=https://books.google.com/books?id=sTZLAAAAQBAJ&pg=PA100 |title=Tibetan Buddhism: A Very Short Introduction |location=New York |publisher=Oxford University Press |page=100 |isbn=978-0-19-973512-9 |lccn=2013006676}}</ref> A similar funerary practice that features excarnation can be found in Zoroastrianism; in order to prevent the pollution of the sacred elements (fire, earth, and water) from contact with decomposing bodies, human cadavers are exposed on the Towers of Silence to be eaten by vultures and wild dogs.<ref>{{cite book |author-last=Huff |author-first=Dietrich |year=2004 |chapter-url=https://books.google.com/books?id=sNqmDwAAQBAJ&pg=PA593 |editor-last=Stausberg |editor-first=Michael |editor-link=Michael Stausberg |title=Zoroastrian Rituals in Context |chapter=Archaeological Evidence of Zoroastrian Funerary Practices |location=Leiden |publisher=Brill Publishers |series=Numen Book Series |volume=102 |pages=593–630 |doi=10.1163/9789047412502_027 |isbn=90-04-13131-0 |issn=0169-8834 |lccn=2003055913}}</ref>
Studies in behavioral ecology and ecological epidemiology have shown that cannibalistic necrophagy, although rare, has been observed as a survival behavior in several social species, including anatomically modern humans;<ref name="Sci. Rep."/> however, episodes of human cannibalism occur rarely in most human societies.<ref name="Sci. Rep."/>{{#tag:ref|For further informations about cannibalistic necrophagy among humans, see the articles ''Homo antecessor'' and List of incidents of cannibalism.|group=Note}} Many instances have occurred in human history, especially in times of war and famine, where necrophagy and human cannibalism emerged as a survival behavior, although anthropologists report the usage of ritual cannibalism among funerary practices and as the preferred means of disposal of the dead in some tribal societies.<ref>{{cite journal |last=Conklin |first=Beth A. |date=February 1995 |title="Thus Are Our Bodies, Thus Was Our Custom": Mortuary Cannibalism in an Amazonian Society |url=https://lauer.sdsu.edu/courses/442-spring-2017/articles/Conklin_1995b.pdf |journal=American Ethnologist |publisher=Wiley |volume=22 |issue=1 |pages=75–101 |doi=10.1525/AE.1995.22.1.02A00040 |jstor=646047 |s2cid=170348254 |archive-url=https://web.archive.org/web/20191211213635/https://lauer.sdsu.edu/courses/442-spring-2017/articles/Conklin_1995b.pdf |archive-date=11 December 2019 |url-status=live |access-date=8 January 2021}}</ref><ref>{{cite journal |last=Vilaça |first=Aparecida |date=January 2000 |title=Relations between Funerary Cannibalism and Warfare Cannibalism: The Question of Predation |journal=Ethnos: Journal of Anthropology |publisher=Taylor & Francis |volume=65 |issue=1 |pages=83–106 |doi=10.1080/001418400360652 |issn=0014-1844 |s2cid=143616841}}</ref><ref>{{cite journal |last=Fausto |first=Carlos |date=August 2007 |title=Feasting on People: Eating Animals and Humans in Amazonia |journal=Current Anthropology |publisher=University of Chicago Press |volume=48 |issue=4 |pages=497–530 |doi=10.1086/518298 |issn=1537-5382 |s2cid=141800146}}</ref>
== Gallery == <gallery mode="packed"> File:White-backed_vultures_eating_a_dead_wildebeest.JPG|White-backed vultures feeding on a carcass of a wildebeest File:Raven scavenging on a dead shark.jpg|A jungle crow feeding on a small dead shark File:Coyoteelk.jpg|Coyote feeding on an elk carcass in winter in Lamar Valley, near Yellowstone National Park File:A polar bear (Ursus maritimus) scavenging a narwhal whale (Monodon monoceros) carcass - journal.pone.0060797.g001-A.png|A polar bear scavenging on a narwhal carcass File:An Ibiza wall lizard (Podarcis pityusensis) scavenging on fish scraps leftover from another predator - journal.pone.0060797.g001-B.png|An Ibiza wall lizard scavenging on fish scraps left over from another predator File:Red weaver ants (Oecophylla smaragdina) feeding on a dead African giant snail (Achatina fulica) - journal.pone.0060797.g001-F.png|Red weaver ants feeding on a dead giant African snail File:Feral dog eating from trash bin in Moscow 01.jpg|A feral dog scavenging for food in a trash bin in Moscow File:Squirrel eating an ice cream cone (3558009610).jpg|A gray squirrel scavenging food scraps from a trash bin in London File:A herd of 40 wild elephants at Ampara in east Sri Lanka is totally dependent on garbage from tractors DSC-9.jpg|Asian elephants scavenging for food at a municipal dump in Sri Lanka </gallery>
== See also == * Consumer-resource systems
==Notes== {{Reflist|group=Note}}
== References == {{Reflist}}
== Further reading == * {{Cite book |last=Smith |first=T. M. |title=Elements of ecology. |date=2015 |others=Robert Leo Smith |isbn=978-1-292-07740-6 |edition=9 |location=Harlow |oclc=915123443}} * {{Cite book |last=Rufus |first=Anneli S. |title=The Scavengers' Manifesto |date=2009 |publisher=Jeremy P. Tarcher/Penguin |others=Kristan Lawson |isbn=978-1-58542-717-8 |location=New York |oclc=262428497}} * {{Cite book |last=Kruuk |first=Hans |title=Hunter and Hunted: Relationships Between Carnivores and People |date=2002 |publisher=Cambridge University Press |isbn=0-511-06485-3 |location=Cambridge, UK |oclc=57254065}} * {{Cite web |title=Tasmanian devil {{!}} Habitat, Population, Size, & Facts {{!}} Britannica |url=https://www.britannica.com/animal/Tasmanian-devil |access-date=2022-10-03 |website=www.britannica.com |language=en}}
== External links == {{Commons category|Scavenging}} * Examples of [https://doi.org/10.5281/zenodo.18399421 vertebrate] and [https://doi.org/10.5281/zenodo.18411534 invertebrate] carrion feeders (species names and dietary information with supporting references) from ''Zenodo'' datasets * [https://www.bbc.com/audio/play/p0mtzz06 Eternal horizons] (a podcast on sky burial) from ''BBC Audio'' * [https://www.nytimes.com/slideshow/2010/09/18/world/americas/0919VENEZ.html Stitching a life from the scraps of others] (a slideshow on scavenging at Cambalache municipal dump in Venezuela) from ''The New York Times'' * [https://www.cbc.ca/radio/quirks/sep-24-the-milky-way-tells-its-story-raccoon-criminal-masterminds-back-to-the-water-and-more-1.6591908/how-trash-bandits-furry-and-feathered-outsmart-humans-for-food-1.6591914 How trash bandits, furry and feathered, outsmart humans for food] (a radio podcast on refuse-eating cockatoos and raccoons) from the ''Canadian Broadcasting Corporation''
{{Feeding}} {{Authority control}}
Category:Ecology Category:Scavengers